John William Gibson, William Henry Crogman, Booker T. Washington, Fannie Barrier Williams (1902). “Progress of a race: or, The remarkable advancement of the American Negro from the bondage of slavery, ignorance and poverty to the freedom of citizenship, intelligence, affluence, honor and trust”
Edward Sapir, David Goodman Mandelbaum (1985). “Selected Writings of Edward Sapir in Language, Culture and Personality”, p.159, Univ of California Press